Allison MT654CR oil leak

[Valor]

I have an Allison MT-654CR trans that is leaking out of a small black tube at the rear of the trans tailshaft. Does anyone know what this tube goes to and why it might be leaking fluid? The truck is a 1990 BMY M923A2. Thanks for your help.

 

[Valor]

Well the Service manual calls it a drain tube. I knew that. Was wondering if anyone has had their trans apart with this same problem. I'm thinking it would be the output shaft seal leaking around the outside diameter. Any ideas?